Circuit interrupter



June 21, 1949. B. P. BAKER ETAL 2,473,843

' CIRCUIT INTERRUPTER Filed Feb. 28, 1945 s Sheets-Sheet 1 I "l i 25* r WITNESSES: INVENTORS' if Ben 00910)? fiarer' and 7V Dona/o C. Harmer:

ATTORNE June 21, 1949. B. P. BAKER ETAL 2,473,843

CIRCUIT INTERRUPTER V Filed Feb. 28, 1945 3 Sheets-Sheet 2 ..I lfllll llllll I| INVENTORS B n 'am/n P50 A er and Dona/d C. Harmer". 6i QJ I ATTORNEY Patented June 21, 1949 CIRCUIT IN TERRUPTER Benjamin P. Baker, Turtle Creek, and Donald C.

Harker, Wilkinsburg, Pa., assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application February 28, 1945, Serial No. 580,136

14 Claims.

1 This invention relates to circuit interrupters, in general, and, more particularly, to operatin mechanisms therefor.

A general object of our invention is to provide an improved operating mechanism for a circuit interrupter which will permit high velocity motion during the initial part of the opening operation yet will permit an absorption of the kinetic energy associated with the high velocity moving parts to minimize the impact forces on the operating mechanism during the stopping of the moving parts.

A more specific object is to provide an improved circuit interrupter of the type employing a gas blast for extinction of the are and to provide a movable inertia element which is connected by means of a lost motion coupling or connection with the movable contact structure of the interrupter.

Another object is to provide a movable inertia element connected by a lost motion coupling or connection with the movable contact to counteract the effect of the high magnetic forces encountered during the interruption of relatively high curren s, of the order of 40,000 amperes or higher.

In a high speed compressed air circuit breaker, it is necessary to obtain a blast valve opening and a finite contact separation just as soon as possible. This must be obtained by large accelerating forces and high velocities. velocities are allowed to continue after optimum interrupting conditions are obtained, unnecessary and damaging arc length and are energy will result. Also, the blast valve which is mechanically tied to the contact mechanism will be closed before a current zero may occur. This hazard is worse at 25 cycle frequency than at 60 cycle frequency in that the wait for a current zero may be greater than ,4, of a second.

Our invention employs the use of a mass or an inertia element which is so proportioned and attached to the contact mechanism through a lost motion coupling or connection, that the initial part of the contact and the openin of the blast valve is obtained at high speed and independently of this mass or inertia element. As soon as optimum interrupting conditions are obtained, the mass or inertia element is engaged which causes a complete hesitation of approximately /30 of a second in the motion of the contact after which the contact and the mass move together at considerably reduced velocity.

By the above arrangement this not only holds the blast valve open and the contact at the best separation until interruption occurs, but it de- If these high creases the velocity and shock on the mechanism which finally arrests the contact motion at the end of its stroke.

In U. S. Patent N0. 1,988,610 which issued J anuary 22, 1935 to Stanley T. Schofield and Samuel H. Boden and which is assigned to the assignee of the instant application, there is shown and claimed a novel circuit interrupting arrangement of the air break type in which the movable contact engages through a spring connection with a movable inertia element to decelerate the moving parts of the interrupter. It is a further object of our invention to improve the mechanism set forth in this patent and to provide an improved construction more adaptable to circuit interrupters of the gas blast type.

Another object of our invention is to provide an improved toggle operating arrangement in which a pair of cooperating compression springs are employed to provide improved spring characteristics to effect the breaking of the toggle during the opening operation. By such an arrangement, the impact forces resulting during the breaking of the toggle are considerably decreased, and consequently the shock on the mechanism is greatly reduced.

Another object is to provide an improved shock absorbing mechanism for the movable parts of a circuit interrupter in which a portion of a mass or inertia element is connected by way of a lost motion coupling or connection to the movable contact and also in which another portion of the mass or inertia element is resiliently mounted with respect to the afore-mentioned portion. Such a relative resilient mounting arrangement between the two portions of the mass or inertia element is especially desirable during the closing operation.

Further objects and advantages will readily become apparent upon a reading of the following specification taken in conjunction with the drawings, in which:

Figure 1 is a side elevational view of a gas blast type of circuit interrupter embodying our invention and shown in the closed circuit position;

Fig. 2 is a fragmentary enlarged side elevational view, partly in section of the improved operating mechanism of the interrupter, the parts being shown in the closed circuit position;

Fig. 3 is a fragmentary plan view of a portion of the operating linkage taken substantially along the line IIIIII of Fig. 2;

Fig. 4 is a fragmentary plan view of a portion of the operation linkage;

Fig. 5 illustrates graphically the improved results of our invention as compared to the result encountered when no shock absorbing mechanism is provided; and

Fig. 6 graphically illustrates the spring charcteristics of the compression springs employed in our improved toggle kick-off arrangement.

Referring to the drawings and more particularly to Fig. 1 thereof, the reference numeral I designates a tank filled with a suitable arc extinguishing gas under pressure, in this instance compressed air. The tank supports at its upper end an outlet conduit 2 which branches at its upper end into further conduits 3, 4. The conduit 3 leads through a valve casing 5 to a blast tube 8, the passage of gas through the valve casing 5 being controlled by a blast valve operating mechanism generally designated by the reference numeral 1.

The upper end of the blast tube 6 terminates adjacent to the contact gap which is formed durtionary contact structure '9, and a second line terminal I l is electrically connected to the movable contact 8.

Consequently, in the closed circuit position of the interrupter, as shown in Figs. 1 and 2, the electrical circuit therethrough comprises the line terminal l0, stationary contact structure 9, movable contact 8 to the other line terminal H of the interrupter. To effect an opening operation of the interrupter, suitable operating mechanism, hereinafter more fully described, is actuated to cause downward movement of an insulating operating rod l2 which is pivotally connected at l3 to the movable contact 8. The lower end of the insulating operating rod 12 is secured by means of a threaded engagement to a metallic U-shaped member M, the lower end of which is bifurcated as at ill to form two opposing legs l6, l1 more clearly shown in Fig. 4 and pivotally mounted on a pin l8. The pin l8 passes through a bifurcated portion I9 of .a high speed operating lever 20, the latter being pivotally mounted on a pin 2| to a pair of hand operating levers 22 rigidly secured together by a bolt 23 to move as a unit.

The hand operating levers 22 are pivotally mounted on pins 24 (see Fig. 4) to a pair of support plates 25, the latter having a configuration more clearly shown in Fig. 1 and spaced apart a distance more clearly shown in Fig. 4.

Referring to Fig. 2, it will be observed that the pin 2'! also pivotally supports a pair of toggle links 26 having a knee pin at 21, the latter passing through the other leg 28 of the toggle which is generally designated by the reference numeral 29. Fig. 2 shows the toggle 29 in its overcenter position in the closed circuit position of the interrupter, an adjustable stop 30 being provided to limit the overcenter travel of the toggle 29.

The lower leg 28 of the toggle 29 is preferably formed as an integral part of a bell crank 3| pivotally mounted at 32 to a stationary pivot and having a lower portion 33 making pivotal connection at 34 to a pair of short links 35. As viewed in Fig. 2, the left-hand ends of the short links 35 make pivotal connection at 36 to a crosshead 31, the latter being movable by a piston rod 38. At the lefthand end of the piston rod 38 is a piston 39 which reciprocally travels in an operatingcylinder 40;

A suitably shaped casting member 4| is secured to the right-hand end 42 of the operating cylinder 40 and has formed therein a pair of guide slots 43 which serve to guide the reciprocating motion of the cross-head 31. Preferably, an upstanding portion 44 of the bifurcated casting member 4! forms a bearing for the stationary pivot pin 32.

The closing motion of the piston 39 is controlled by a magnetic closing valve 45 which permits the admission of compressed air to the piston contained in a main closing valve 46, the latter controlling the admission of fluid from a reservoir 47 leading from the tank I to the lefthand end of the operating cylinder 40.

It will be observed, referring to Fig. 2, that the conduit 3 leads into the valve casing 5, the passage of compressed air therethrough being controlled by a blast valve 48 having a stem 49. The valve stem 49 makes a pivotal connection at 50 to an actuating member 5| pivotally mounted at 52 to the wall 53 of the valve casing 5, a compression spring 54 serving to bias the actuating arm 51 in a clockwise direction about its pivotal mounting 52 to eifectclosing of the blast valve 48.

The particular blast valve operating mechanism shown forms no part of our invention and may be of any suitable type. Preferably, it is of the adjustable roller type similar to that illustrated and claimed in U. S. Patent No. 2,310,779 which issued February :9, 1943 to Erik H. Hall and Raymond B. Leitzel and which is assigned to the assignee of the instant application. However, since our invention is not concerned with the blast valve mechanism it has been simplified for purposes of illustration and comprises a pair of opposed externally extending arms 55 between which is disposed a roller 56 mounted on a pin 51.

The roller 57, in the closed circuit position of the interrupter as shown in Fig. 2, comes closely adjacent to a cam surface 58 of the high speed operating lever 20, the latter having a bifurcated portion 59 (see Fig. 4) between the legs of which is positioned a roller 60. The roller 80 of the high speed operating lever :20 is latched in position by a latch mechanism generally designated by the reference numeral 6 l.

The latch mechanism 6| comprises an opposed pair of latch levers 62 pivotally mounted on a stationary pivot at 63 .and making pivotal connection at 64 to a spring guide rod 65, the latter passing through a fixed support plate 66. Two compression springs :61, 68 are mounted on the spring guide rod and serve to bias the latch levels '62 in a counter-clockwise direction about the fixed pivot pin 63.

Extending between the latch levers 62 is a trigger lever 69 pivotally mounted on a stationary pivot at 1-0 and biased in a clockwise direction thereabout by a compression spring H. The right-hand end of the trigger lever 69 forms a latch 12 which in the closed circuit position of the interrupter, as shown in Fig. 2, abuts against a latch member 13. The latch lever 13 is pivotally mounted about the pin 63 and is biased in a clockwise direction thereabout by a compression spring 14. The latch levers 62 have extending portions 15 between which are fixedly secured a guide member 16. The latch member 13 has a latching portion 11 which serves to latch in position the roller .60. A solenoid 18 is employed to effect tripping motion ofthe trigger lever 69 during the opening operation. When the solenoid 18 is thus energized, the trigger lever 69 rotates in a counterclockwise direction about the pivot 10 against the biasing action exerted by the compression spring H to permit the latch member 13 to be rotatedina counterclockwise direction about the pivot pin 63 against the biasing action exerted by the compression spring 14. This occurs because of the biasing action exerted by the opening accelerating springs 19 transmitted through the accelerating rod 88 and link 8| through the pin I8 to bias the high speed trip lever 28 in a clockwise direction about the pivot pin 2|, which remains stationary during the initial portion of the opening operation.

Thus, upon release of the latch mechanism 6|, there is immediately effected clockwise rotation of the high speed trip lever 28 about the pin 2i which during this complete clockwise rotation of the operating lever 28 remains stationary. It will be noted that clockwise rotation of the high speed Operating lever 28 about the pin 2| following unlatching of the roller 68 by the latch mechanism 6| causes downward movement of legs I6, I! to effect through the operating rod I2 opening clockwise rotation of the movable contact 8 away from the stationary contact 9 around the pivot pin 82. Simultaneously, the cam portion 58 of high speed operating lever 28 strikes the roller 51 of the valve mechanism 1 to efiect opening of the blast valve 48 against the biasing action exerted by the gas pressure and the compression spring 54. Thus, opening motion of the blast valve 48 is synchronized with opening motion of the movable contact 8.

The opening of the blast valve 48 permits compressed gas to pass from the conduit 8 through the valve casing 5, upwardly through the blast tube 6 to effect extinction of the arc drawn at the top of the blast tube 6 between the movable contact 8 and the stationary contact 9. Preferably a suitable interrupting structure generally designated by the reference numeral 88 and preferably comprising notched spitters is employed in conjunction with the upward blast of gas. The interrupting structure 83 forms no part of our invention but is preferably of a type set forth and claimed in U. S. Patent No. 2,272,380 which issued February 10, 1942 to Leon R. Ludwig, Herbert L. Rawlins and Benjamin P. Baker and which is assigned to the assignee of the instant application.

During the interruption of relatively high currents, such as of the order of 40,000 amperes, and especially when interrupting alternating currents of a frequency of cycles per second, the

magnetic forces encountered during the opening motion of the contacts are considerable because of the loop effect of the current. Thus, if no provision is made to take care of the extremely high forces involved due to this magnetic action, a travel curve is obtained as indicated by the reference numeral 84 in Fig. 5. It will be observed that the slope of the travel curve 88 is proportional to the contact velocity; consequently, if no means are provided to absorb the high kinetic energies involved, extremely high velocities of the movable parts are encountered, as indicated by the travel curve 84. I

To overcome the high kinetic energies involved as a result of the high magneto forces encountered, we provide the kinetic energy absorbing mechanism generally designated by the reference numeral 85 and comprising a mass or inertia element 86 associated with a rod 81 connected by a lost motion coupling or mechanical connection 88 to the movable contact 8. More specifically, the mass or inertia element 86 consists of several metallic discs 89 of relatively large weight threadedly secured at 98 to the left-hand end 9i of the rod 81. A nut 92 may also be provided. Loosely mounted on the rod 81 are a disc-like resilient member 93, in this instance composed of leather, and one or more movable weight discs 94. Both the leather ring 93 and the metallic weight ring 94 are loosely mounted on the portion 95 of the rod 81, a compression spring 98 biasing the rings 93, 94 against the fixed discs 89. The right-hand end of the compression spring 96 seats against a flange 91 rigidly fixed to the rod 81. Preferably, to relieve some of the weight which must be supported by the rod 8?, the lefthand disc 89 has a lug 98 fixed thereto which is pivotally connected at 99 to a pair of links I88, the upper ends of which are pivotally mounted at iiii to a fixed support I'82 which is preferably a portion of the supporting framework of the interrupter. Consequently, the additional support means I83 relieves the stress imposed on the rod 81, but nevertheless permits substantial axial movement of the rod 81 with respect to the fixed support I82.

The right-hand end of the rod 81 is threadedly secured to a bifurcated member I84 more clearly shown in Fig. 3 through which passes two pins l85, 85. The pin I pivotally mounts a lever 58? to the bifurcated rod end I84 and hence to the rod 81. The lever I8! is preferably formed as an integral part of a cylinder I88 having a lever I89 integrally formed therewith adjacent the intermediate portion of the cylinder I88, as shown more clearly in Fig. 3. The cylindrical bearing I88 is pivotally mounted on a pin II8 which extends through the two support plates 25 being supported thereby.

The lever N19 has a pin III extending therethrough, the pin I I I being slidably guided in two slots I I2 formed in two links I I3, the upper ends of which are pivotally mounted at I I4 to a downwardly projecting portion I I5 of a spring-follower member H6, the latter being biased downwardly by the opening accelerating spring 19 and being movable within the spring-guide cylinder Ill.

The pin [88 pivotally mounts the bifurcated link I I8 to the bifurcated rod end I84. A pin I 29 which extends through the two legs I28, I2I of the bifurcated link II8 pivotally mounts a link I22, the right-hand end of which is fixed to a shaft I23, the latter extending within a shock absorbing cylinder I 24. The mechanism within the shock absorbing cylinder I24 is such as to inhibit rotative motion of the shaft I23 and supplements the shock absorbing action which takes place in the kinetic energy absorbing mechanism 85.

It will be observed that because of the lost motion coupling 88 the initial opening travel of the movable contact 8 is not impeded. Consequently, in the operation of our interrupter, we obtain an initial travel curve I25 of Fig. 5 which would develop into the travel curve 84, should no decelerating mechanism be provided. However, at the point P in Fig. 5, the top of the slots H2 strike the pin HI to immediately bring into action both the shock absorbing mechanism I24 and the kinetic energy absorbing mechanism 85 to result in the modified travel curve I28 of Fig. 5. There may occur at high currents, such as 48,000 amperes or over, a slight bounce, as indicated by the hump portion I21 of the travel curve I28. However, despite this possibility, the modified travel curve I26 of Fig. 5 considerably reduces the opening velocity of the movable parts of the interrupter after the point P is reached. Consequently, the shock is removed from the op erating mechanism, and the contacts are slowed down or substantially halted sufiiciently in the space of time represented by t, as shown in Fig,

5, when the blast valve is open to effect interruption at a current zero.

Thus, by employing our invention, we quickly obtain the optimum contact gap necessary for interruption, designated by the point P, and immediately when this optimum contact gap is obtained, slow down the mechanism so that there will surely be time enough for a current Zero to occur. Without employing such a decelerating mechanism, difficulties were encountered inasmuch as the extremely high velocity of the contact parts during the interruption of highamperage currents on 25 cycles permitted the camsurface 58 of the operating lever 20 to ride off of the roller 5'5 of the blast valve mechanism I permitting the blast valve to close even before a current zero had been obtained. But by employing the kinetic energy absorbing mechanism 85 in conjunction with the shock absorber I24, the contact velocity is reduced to such an extent following the attainment of a sufiicient contact gap of optimum dimensions that a current zero will surely occur, and consequently, interruption of the circuit at this current zero will ensue.

It is to be noted that the high speed operating lever completes its clockwise rotative' travel about the pivot 2I efiectin interruption of the circuit and bringing the movable contact 8 to a complete halt before any motion takes place whatsoever of the main operating levers 22'. Thus, upon completion of the clockwise rotative motion of the high speed operating lever 20 about the pivot 2I until the flange I23 secured to the accelerating rod 80 strikes the leather washer I29, then and then only do the operating levers move in a clockwise direction about the pivot pins 24 (see Fig. 4).

This results inasmuch as when the flange I28 strikes the resilient washer I29 the compressive forces tending to hold the toggle 29 in its overcenter position, as shown in Fig. 2, are reduced to such an extent that then and then only is the relatively weak biasing means I30 associated with the toggle kick-off rod I3I sufficient to effect breakage of the toggle 29 to thereby rotate the bell crank 3! about its pivot 32 in a clockwise direction to effect leftward movement of the piston 39.

Thus, to retrieve the closing linkage of the main circuit breaker operating mechanism, the kick-out ias means I39 is used to push the linkage overtoggle and to cause the toggle lever 31' to rotate clockwise about point 32 assisted by the weight of the high speed lever 29 and the main operating levels 22.

Initially, considerable force is required to raise these weights as the linkage comes into toggle and to overcome static friction. If a single spring is used which is suiiiciently strong to overcome these forces, it provides too much energy after the linkage goes overtoggle and so results in too much of an impact force on the linkage at the end of the opening stroke. Moreover, the static friction forces are widely variable depending on the con dition of the various bearings and the impact with which the linkage has been closed. These static friction forces are a considerable portion to the total force required. I

By using two compression springs I32, I33 in series, one a short stiff spring I32, and another a. weaker longer spring I33, which goes solid near the end of the closing stroke, a high initial force is available for breaking the static friction load and raising the weight of the linkage overtoggle', While at the same time providing a more modersite force for following through the linkage to the openposition. Referring to Fig. 6 and remembering that the energy imparted to the linkage is the area under the curves, it is evident that the area under curve RST is considerably less than under curve RT, and hence there is considerably less impact to the linkage when it reaches the open position.

An additional advantage of the invention lies in the fact that manufacturing variations which may introduce considerable different initial loads are readily adjusted by putting a washer or Washers I34 under the stiff spring. This is not the case for a single spring. (Compare d and d!',1.)

Following the breaking of the toggle 29, the high speed operating lever 20 is rotated in a counterclockwise direction about the pivot pin I8, which during this time is stationary, flange I28 having struck and thereby having been stopped by the leather washer I29. This counterclockwise travel of the high speed lever 28 continues until the roller 60 attached thereto (Fig. 4) strikes the tongue I6, thereby moving the latch levers 62 in a clockwise direction about the pivot pin 63 permitting the compression spring 14 to force the latch lever 62 over the roller 60 and thus permitting the trigger lever 69 to be rotated in a clockwise direction about the pin I0 by the compression spring II. Thus, the high speed trip lever 263 is relatched by the latch mechanism BI at the end of the opening stroke of the interrupter.

To close the interrupter, the magnetic closing valve is operated by means not shown to thereby permit operation of the closing valve 46 to permit compressed gas to pass from the reservoir 4'! to the left-hand end of the operating cylinder 40 to force the piston 39 toward the right. This effects rightward movement of the piston rod 38 and correspondingly rightward movement of the cross-head 3'! to effect extension of the toggle 2'9 and consequently counterclockwise rotation of both the high-speed lever 29 and the operating arms 22 about their concentric axes of rotation, pins 24 and roller 60.

This effects upward movement of the operating rod end I5 to effect contact closure while simultaneously effecting compression of the accelerating compression springs I9.

Also, this closing motion forces the rod 81 to the left, thereby moving only the discs 89, the compression spring 96 being relied upon to effect closing motion of the disc 93, 94 thereafter. Consequently, the closing operation is not effected by the Weight of the disc 94 which is freely slidable upon the rod 81. Durin the opening operation, the disc 94 is picked up by the discs 89 through the energy absorption member 93.

The invention has a distinct advantage when closing against a high current, for the magnetic forces involved by spark-over near the end of the closing stroke tend to slow down the closing movement of the movable contact 8. However, the inertia mass 86 continues to move to the left causing the pin I I I to strike the upper end of the slots I I2 during such a final portion of the closing stroke to give a final impact force to the movable contact 8 near the end of the closing stroke to force it into engagement with the stationary contact 9.

Thus, the mass 86 is so proportioned that in comparison with the magnetic forces and masses of the moving parts of the breaker that a hesitation of the contact motion is produced sufficiently long to allow for circuit interruption with the contact separation at its optimum value for arc extinction. This hesitation also makes it possible to obtain extremely high accelerations and high velocities to obtain this optimum contact separation and then slow down the mechanism to the point where the energies which have to be absorbed in the full open position of the breaker do not damage the mechanism.

It is desirable to arrest the high speed motion of the contact 8 when the conditions are right for are extinction so that the blast valve 48 will not be permitted to reclose before a current zero is reached and are extinction can be obtained. The difference between no-load and full load acceleration produced by the magnetic forces is very great.

The advantages obtained by the use of the mass or inertia element 86 are:

1. To hold the contacts separated at their optimum value for are extinction until a current zero is reached, regardless of the magnitude of the current and magnetic forces;

2. To permit high accelerations and high velocities through the early part of the opening stroke and then to decrease this velocity by increasing the mass of the moving system, so that the entire system will approach its final open position with a greatly reduced velocity and consequently a correspondingly reduced energy;

3. To obtain hesitation in the mechanism which controls the blast valve operation, so that flow of air for are extinction is insured at the time of zero current.

4. To provide an impact force on the movable contact near the end of the closing stroke to overcome the magnetic forces involved by sparkover at this time, when closing against extremely high currents. This results since the magnetic forces will tend to impede the final closing motion of the movable contact, and at this time the inertia mass will take up the play in the lost motion connection to strike the movable contact, thereby forcing it into engagement with the stationary contact structure despite the effect of the magnetic forces which impede the closing operation.

5. To provide the effect of a large mass as a part of the moving contact system for closing operation, but not for the early portion of the opening operation so that the high pressures in the closing cylinder may be used in the closing operation without producing excessive and damaging velocities to the additional inertia attached to the moving system during the closing operation. This reduces the contact speed to a desirable value and at the same time permits high pressures in the closing cylinder so that when magnetic forces are encountered, as a result of spark-over in the interrupter, very large forces are available in the closing mechanism to instantly overcome these magnetic reactions.

From the foregoing description, it is apparent that the mass 86 is so arranged that a part of it is rigidly secured to the rod 8'! whilepart of it is slidably mounted on the rod 81 with a resilient member 93 between the slidably mounted portion and the fixed portion so that when the rigidly attached mass is engaged the slidably mounted mass is then engaged through the resilient member; this consequently decreases the shock on the mechanism. Likewise, increasing the speed of the closing of the breaker is not affected by the portion of the mass 86 which is slidably mounted on the rod 81, the latter portion of the mass being forced to follow the rigidly attached portion 89 by the action of the compression spring 95. The force of the compression spring 96 is adjusted so that if the breaker is required to make an opening operation immediately following a closing operation, the slidably mounted mass will have reached the end of its stroke sometime later than the rigidly attached mass, but before the motion of the contacts has reversed.

Certain features of the operating mechanism relating to the high speed rotation of the high speed operating lever 20 together with the synchronized opening of the blast valve 28 thereby are described and claimed in a concurrently filed application by Howard M. Wilcox and Raymond I-I. Leitzel, Serial No. 580,138 now Patent No. 2,498,482, issued Oct. 7, 1947, and assigned to the assignee of the instant application.

From the foregoing description, it will be apparent that we have provided a mass or inertia element which is engaged through a lost motion coupling or connection during the opening operation, but which is not engaged by a lost motion coupling during the closing operation. It will also be apparent that we have provided an improved toggle breaking arrangement which minimizes the impact forces produced. Further, it is to be observed that we have counteracted the effect of high magnetic forces involved during the interruption of high ampereage currents.

Although We have shown and described a specific structure, it is to be clearly understood that the same was merely for the purpose of illustration and that changes and modifications may readily be made therein by those skilled in the art Without departing from the spirit and scope of the appended claims.

We claim as our invention:

1. In a circuit interrupter, a movable contact, means for moving the movable contact to open and closed positions at high speed, a rod, an inertia mass having one portion secured to the rod and having another portion loosely mounted on the rod so as to be movable relative thereto, a

compression spring mounted on the rod and having one end seated rigidly with respect to the rod and having the other end biasing the loosely mounted portion against the first-mentioned portion, and a lost-motion mechanical connection between the movable contact and the rod arranged to impart movement to said rod and inertia mass following a predetermined contact movement in the opening direction, said spring enabling move-' ment of said loosely mounted portion with respect to said secured portion to reduce the inertia effect of said mass during the initial closing movement of said contact.

2. In a circuit interrupter, a movable contact, means for moving the movable contact to open and closed positions at high speed, a rod, an inertia mass having one portion secured to the rod and having another portion loosely mounted on the rod so as to be movable relative thereto, a compression spring mounted on the rod and having one end seated rigidly with respect to the rod and having the other end biasing the loosely mounted portion against the first-mentioned portion, a lostmotion mechanical connection between the movable contact and the rod arranged to impart movement to said rod and inertia mass following'a predetermined contact movement in the opening direction, said spring enabling movement of said loosely mounted portion with respect to said secured portion to reduce the inertia effect of said mass during the initial closing movementof saidcontact, and a resilient member interposed between the two portions.

3. In a circuit interrupter, a movable contact, means for moving the movable contact to open and closed positions at high speed, a rod, an inertia mass having one portion secured to the rod and having another portion loosely mounted on the rod so as to be movable relative thereto, a compression spring mounted on the rod and having one end thereof seated rigidly with respect to the rod and having the other end biasing the loosely mounted portion against the first-memtioned portion, a lost-motion mechanical connection between the movable contact and the rod to actuate said inertia mass to thereby reduce the contact opening speed following a predetermined movement in the opening direction and to assist said contact moving means in moving said contact to closed position, and a shock absorber operatively associated with said rod and actuated at the same time the rod is actuated by the movable contact.

4. In a circuit interrupter, a movable contact, means for moving the movable contact to open and closed positions at high speed, a rod, an inertia mass having one portion secured to the rod' and having another portion loosely mounted on the rod so as to be movable relative thereto, a compression spring mounted on the rod and having one end seated rigidly with respect to the rod and having the other end biasing the loosely mounted portion against the first-mentioned portion, a lost-motion mechanical connection between the movable contact and the rod whereby said inertia mass reduces the contact. opening speed following a predetermined movement in the opening direction and assists said contact moving means in moving said contact to closed position, a' resilient member interposed between the two portions, and a shock absorber coupled to said: rod and actuated at the same time the rod is: actuated by the movable contact.

5. In a. circuit interrupter, a movable contact,

mentioned. portiorr thereof so that during apart of the opening operation the two portions move. together; and during the closing operation the movement of the second-mentioned portion is delayed with respect to the. first-mentioned portion.

6. In a. circuit interrupter, a relatively light moving contact system, a relatively heavy inertia system, operating means including a. toggle for operating said contact system, piston means for actuating. said toggle-to effect closing motion of both the relatively light moving contact system and the relatively heavy inertia system, a lost motion connection. mechanically connecting the relatively light moving contact system and the relatively heavy inertia system, the relatively heavy inertia system comprising a. first portion and a second portion, and resilient means between. the two portions.

7'. In a circuit. interrupter of the gas blast type, a relatively light moving contact system, a relatively heavy inertia. system, a lost motion connection mechanically connecting the aforementioned two systems, operating means including a toggle for effecting closing motion of both the aforementioned two. systems, piston. means for actuating said: toggle to effect. closing motion of the operating means, the arrangement having the lost motion connection effective during the opening operation to delay actuation of said inertia system and eifective during the closing operation when; closing against. heavy currents to cause said inertiav system to assist said operating means in the closing operation.

8. In a circuit interrupter, movable contact means, operating mechanism for effecting highspeed opening. and closing movement of said movable contact means, an inertia mass, a movable member to which at least a portion of said inertia mass is rigidly secured, a lost motion coupling connecting said movable member to' said movable contact means to cause said inertia mass to decelerate the movement of said movable contact means during opening movement after said movable contact means has moved a predetermined distance, said lost motion coupling causing said inertia mass to decelerate movement of said movable contact means during closing movement after said movable contact means has moved a predetermined distance, and said lost motion coupling thereafter during said closing movement ransmitting kinetic energy from said inertia mass to said movable contact means'to assist said operating mechanism in moving said movable contact means to the closed position;

9. In a circuit interrupter comprising movable contact means, means for effecting high-speed opening and closing movements of said' movable contact means, a longitudinally movable member, afirst inertia mass rigidly secured to one end of said member, a second inertia. mass mounted on said longitudinally movable member adjacent said first inertia mass, a lost-motion coupling connecting the other end of said longitudinally movable member and said movable contact means in a manner to cause said contact means to pick up said inertia masses after a predetermined travel in opening direction to thereby decelerate the opening movement of said contact means and to cause said contact means to pick up said first inertia mass after apredetermined travel in closing direction to decelerate the closing movement of said contact means, and said longitudinally movable member being movable relative to said second inertia mass mounted thereon during the closing movement of said contact means to thereby provide less deceleration of said contact means during closing movement than during opening movement of said contact means.

10-: In a. circuit interrupter comprising movable contact means, means for effecting high-speed opening and? closing movements of said contact means, a movable member, a first inertia mass rigidly secured to saidmovable member, a second inertia mass loosely mounted on said movable member adjacent said first inertia mass, a lostmotion coupling connecting said movable memher to said movable contact means in a manner tocause said movable contact means to pick up both of said inertia masses after a predetermined travel in opening direction to decelerate opening movement of said movable contact means and to cause said movable contact means to pick up said first inertia mass after a predetermined travel in closing direction to decelerate the closing movement or said movable contact means, and resilient means between said movable member and said second inertia mass to permit movement of said movable member relative to'said second inertia mass during closing" movement of said movable contact means to thereby provide less decel-- 13 eration of said movable contact means during closing movement than during opening movement of said movable contact means.

11. In a circuit interrupter comprising movable contact means, means for eiiecting high-speed opening and closing movement of said movable contact means, decelerating means for decelerating both opening and closing movements of said movable contact means comprising a movable member, an inertia mass comprising a first portion rigidly fixed to said movable member and. a second portion loosely mounted on said movable member, a lost motion coupling comprising a pin and slot connection coupling said movable member to said movable contact means to cause said inertia mass to decelerate opening movement of said movable contact means at a predetermined time during said opening movement and to cause said first portion of said inertia mass to decelerate the closing movement of said movable contact means at a predetermined time during said closing movement, and said movable member being movable relative to said second portion of said inertia mass during the closing movement of said movable contact means to decrease the decelerating effect of said inertia mass during closing movement of said movable contact means.

12. In a circuit interrupter, movable contact means, operating means for effecting high-speed opening and closing movement of said movable contact means, decelerating means for decelerating both the opening and closing movements of said movable contact means comprising a movable member, an inertia mass including a first mass fixedly secured to said movable member and a second mass loosely mounted on said movable member adjacent said first mass, a lost motion coupling connecting said movable member to said movable contact means to cause said decelerating means to decelerate the opening and closing movements of said movable contact means at a predetermined time during each movement, said movable member being movable relative to said second mass during the closing movement to decrease the decelerating effect of said decelerating means during the closing movement of said movable contact means, spring means for returning said second inertia mass to its initial position, and both of said inertia masses being effective during the closing movement when closing against heavy currents to assist said operating means in closing said movable contact means.

13. In a circuit interrupter, movable contact means for drawing an arc, a blast valve for directing an arc extinguishing blast of gas to extinguish said arc, operating means for effecting high speed opening and closing movement of said movable contact means and said blast valve, means comprising an inertia member for decelerating the opening and closing movements of said movable contact means, a lost motion coupling connecting said inertia member to said movable contact means to cause said inertia member to decelerate the opening movement of said movable contact means only after said blast valve has opened and said movable contact has opened to a predetermined point most favorable for are extinction, and said lost motion coupling causing said inertia member to first decelerate the closing movement of said movable contact means and then assist said operating means to move said movable contact means to the closed position.

14. In a circuit interrupter, stationary and movable contact means for drawing an arc, a blast valve for directing an arc extinguishing blast of gas to extinguish said arc, means for eifecting high-speed opening and closing movement of said movable contact and opening of said blast valve, decelerating means comprising an inertia member for decelerating both the opening and closing movements of said movable contact means, a lost motion coupling connecting said inertia member to said movable contact means to cause said decelerating means to decelerate the opening movement of said movable contact only after said blast valve has opened and said movable contact has opened a predetermined distance to a point most favorable for arc extinction, and said lost motion coupling causing said inertia member to decelerate the closing movement of said movable contact.

BENJAMIN P. BAKER. DONALD C. HARKER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,182,381 Kaplan May 9, 1916 1,243,526 Hughes Oct. 16, 1917 1,501,382 Whisler July 1, 1924 1,816,799 Upp et a1 July 28, 1931 1,988,610 Schofield et a1 Jan. 22, 1935 2,303,443 Dufiing et a1 Dec. 1, 1942 2,310,779 Hall et a1 Feb. 9, 1943 FOREIGN PATENTS Number Country Date 520,830 Great Britain May 6, 1940 

